This project is mainly concerned with the development of physical techniques for the study of DNA and chromosomes in higher organisms. Specifically, we are in the process of developing methods for separating chromosmal DNA molecules. The methods currently under investigation involve radical modifications of gel electrophoresis and column chromatography techniques. Such separations, if they can be accomplished, will allow molecular biologists to study and map the DNA of individual chromosomes. We are also in the process of further refining viscoelastic molecular weight measurements of chromosomal DNA. Physical studies of DNA renaturation kinetics and hybridizations are being continued.